Bluetooth Low Energy (BLE) is, in its current form, a low-power, low-cost, and low-rate radio communication technique targeting, e.g., sensor applications and wearables. BLE operates in the unlicensed 2.4 GHz industrial, scientific, and medical (ISM) band. The ISM band, e.g. in the 2.4 GHz band, is practically available world-wide and the operation in the band is subject to local regulatory requirements. For example, the regulatory rules are determined by the FCC and ETSI in the US and Europe, respectively. BLE communication takes place over two different types of channels, namely the access beacon channels and the data channels; there are three access beacon channels and 37 data channels available. The access beacon channels are used, e.g., for broadcasting of information and/or for connection setup whereas the data channels are used for communication between two connected devices. There are two ways to communicate in systems like BLE. The first way relies on access beacon messages or events: one device sends (control and/or data) information to one or more other devices; the one or more other devices can act on this information (e.g. by processing the received information, by reacting with an access beacon event of its own, etc.) or request to connect to the device transmitting the access beacon. The second way of communication is based on connections or connection events, wherein two connected devices can exchange packets. It can be said that access beacon messages or events are unidirectional, while communication based on connections or connection events are bidirectional. It can be further said that for an access beacon to be carried out, no connection needs to be in place, such that an access beacon event can also be regarded as a type of random access messages towards one or more other devices, without however the obligation by the other device(s) to respond to such access beacon message even when that message has been correctly received or processed. As to the difference between transmitting the access beacon and connection events, reference is also made to the Bluetooth specification, see e.g. Covered Core Package version 4.2, Volume 1, part A, 1.2 or volume 2 thereof.
Slow frequency hopping is used for both the access beacon channels and the data channels. On the access beacon channels all transmissions are typically repeated three times; once per access beacon channel. The channel used for data communication is changed at regular intervals, each connection interval, but two communicating devices typically have time to exchange several packets on the same channel before it is time to change to a new channel.
FIG. 1 shows a schematic overview of the legacy physical (PHY) layer packet processing for transmitting the access beacon. The link layer (LL) PDU is delivered down from the link layer to the physical layer and is there referred to as the PHY layer SDU. To this SDU a CRC, calculated over the PHY SDU (LL PDU), is added and an access address (AA) and a preamble are appended in front. In legacy BLE all transmissions over the access beacon channels use a fixed, pre-defined access address and a fixed, pre-defined preamble. The PHY SDU (which will also be referred to as an access beacon packet) is transmitted over the air using one access beacon channel amongst those channels available as access beacon channels. Thus, it may be sufficient for a receiver to receive the access beacon packet on a single frequency. Access beacon events are described in detail in the Bluetooth specification version 4.2, see e.g. the above mentioned standard in particular Vol. 6, part B, 4.4.2.
To make BLE technology applicable to a wider range of use cases one may envision several possible improvements to the technology. One constraint for such updates is that the technology also after the update should comply with the regulatory requirements in the ISM band. Another requirement, which is voluntary in nature but still desirable, is that the update considers backwards compatibility; loosely speaking this implies that it should allow for the co-existence of both legacy and new devices in the same network without compromising the performance. Similarly, if a device supporting the new set of features attempts to access a legacy network, this should not compromise the performance of the legacy network.
One possible technology development is the introduction of higher rates. Such a change would make BLE a candidate for services that require higher data rates compared to what is currently supported. A further possible development relates to improving the capacity of such communication systems, e.g. increasing the number of devices that can be concurrently be present in a communication system, without impairing communication, or by reducing the level of impairment that can be caused on other devices. Another possible development is communication over longer range. Longer range may be realized, e.g., by improving the sensitivity, or increasing the maximum allowed output power. In the following, focus will be on the challenges underlying a desired increase of range, and in particular on an increase in the maximum allowed output power as a way to achieve such longer range. Conceptually, it is relatively easy to increase the output power, in the sense that it suffices to introduce a radio section capable of sending more power (i.e. a stronger signal) into the air, for instance from the present 10 dBm (10 mW) to an increased maximum allowed power of up to e.g. 20 dBm (100 mW) or e.g. 30 dBM (1 W) (when noting that similar considerations would apply also to other values higher than the current 10 dBm limit). However, one of the problems lies in dealing with the communication impairment (like interferences, collisions, etc.) that a higher power level may cause to other devices operating in the ISM/2.4 GHz band. It can thus be said that, in general, it is desirable to improve existing systems by reducing the level of impairment caused on other devices.
It is therefore desirable to provide improved method(s), entities, computer programs and system, which overcome, or at least mitigate, the above-mentioned problems when wanting to improve communication systems like present BLE.